Telephone talking-coil and circuit connections.



J. P. FERRITER. TELEPHO'NE TALKING COIL AND CIRCUIT CONNEQT IONS. APPLIYCATION FILED SEPT.20, 1916.

1234,651; Patented July 24,1917.

WITNESSES- mmvm/i' c/AP/Z '6 M9720 By UNITED STATES PATENT OFFICE.

JOHN PATRICK FERRITER, OF JACKSONVILLE, FLORIDA, ASSIGNOR OF ONE-HALF T0- THOMAS J. PETERS, OF PETERS, FLORIDA.

TELEPHONE TALKING-COIL AND CIRCUIT CONNECTIONS.

To all whom it may concern.-

.Be it known that I, JOHN P. FERRITER, a citizen of the United States, and a'resident of Jacksonville, in the county of Duval and State of Florida, have invented a new and Improved Telephone Talking-Coil and Circuit Connections, of which the following is a full, clear, and exact description.

This invention relates to telephony, and deals particularly with an improved talking coil and circuit connections therefor.

The object of the invention is to produce a simple, novel and efficient talking coil which produces a greater amplitude of variation in the current induced in the talking coil secondary winding when the transmitter is in operation than can be produced with an ordinary talking coil and ordinary connections, the current flow being the same in both cases.

In carrying outthe invention, the talking coil has two primary windings consisting of a twisted pair of wires wound around an iron core, which may be open or closed, and a secondary winding of one wire wound over the primaries. An opposite end of each primary winding is connected to the same pole of a battery. The other end of one primary winding is connected to the opposite pole of the battery through one winding of acne to one transformer and a resistance in series with it, which resistance is equal to the resistance of the transmitter when the transmitter is at rest. The second end of the other primary winding is connected to the same battery terminal through the. second winding of the transformer and the transmitter, in series.

For a more complete understanding of the invention reference is to be had to the following description and claims taken in connection with the accompanying drawing, which illustrates certain embodiments of the invention and wherein similar characters of reference indicate corresponding parts in both the views, in which Figure 1 is a diagrammatic view of the.

telephone talking coil and circuitconnections with a carbon transmitter or any other equivalent type, whose actions depends upon the variation of resistance between the electrodes; and

Fig. 2 is a similar view showing a condenser transmitter and a balancing condenser the two branches of the primary circuit.

Specification of Letters Patent,

Referring to the drawing, A designatesa talking coil which has two primary wind-' ing is shown to one side of the primary windings. The primary windings comprise a twisted pair of wires, and one end of one winding and the opposite end of the other winding are connected by a wire 1 with one pole or terminal of a battery or other source of continuous current B. The other terminals of the primary windings are connected respectively with the wires 2 and 3, which are connected by a common wire 4 with the opposite pole or. terminal of the battery B. Included in the wires 2 and b are transformer windings t t wound around an annular core 5 and having a transforming relation of one to one. In the wire 3 is an ordinary carbon transmitter 6, and in the oppo- In the circuit connection shown in Fig. 2

a condenser transmitter 6 is shown in one branch of the primary circuit, and this is balanced by a condenser 7 of the same normal capacity as the condenser 6 The ac- Patented July 24, 1917. Application filed September 20, 1916. Serial No. 121,143. I

tion is substantially the same as in the first arrangement.

The operatlon 1s asfollows:

WVhen the transmitter is at rest, a current 1 passes from the battery through the primary windings in opposite directions and sets up no magnetic action in the core. This is due to the primaries consisting of a twisted pair,

which places both wires in exactly the same relationto the core, no matterhow they are wound. when the transmitter is at rest precludes the possibility of magnetic saturation of the core, which is a seriousfault inherent in ordinary talking coils and which conduces to sluggishness of action. This sluggishness of action aids in producing side tones in the receiver and also contributes to the. distor- This absence of magnetic effect tion of' the electrical wavesproduced by the action of the transmitter, the result being defective articulation in thereceived-signals. Ido not claim that this is the only cause of defective articulation, but that it is a consistance balance of the Wheatstone bridge arrangement of which it is a part and allows of a preponderance 'of current passing through one of the primary windings of the talking coil, which one depending upon whether the transmitter has more or less resistance than the resistance coil in the opposite arm of the bridge. It will be seen readily that, although this action does not set up true alternating currents in the talking coil primaries, it does actually set up alternations in the magnetic lines of force in the core. It could not be otherwise, because, when the transmitter is at rest, there are no magnetic lines of force in the core, while, when the transmitter is in action, the lines of force must necessarily be set up in correspondence with the transmitter variation from a subnormal to a supranormal resistance.

This action of the coil is a great advantage over other types of coil, but it does not increase the amplitude of current produced in the secondary winding; it only quickens the action by relieving the. core of magnetic saturation.

The object of placing a transformer in the circuit is to double the efiect in the talking coil secondary of any inequality of po tential applied to one or the other of the primaries. This is done in the following manner:

A preponderance of current produced by the action of the transmitter, which, in a talking current, is always a momentary impulse, in passin through one arm of the bridge, necessari y passes through one winding of the transformer. This impulse induces a corresponding impulse in the opposite winding of the transformer and in the opposite direction. The strength of this induced impulse will be practically the same as that of the impulse inducing it and it will oppose the current passing through the bridge arm opposite to the arm carrying the original impulse. This opposition will, in effect, double the magnetic efi'ect in the core produced by the original impulse and cause a current to pass through the secondary winding which will have twice the amperage that can be produced in an ordinary coil,

using the same transmitter with the same amount of current passing through the transmitter. The action of this arrangement can be shown to be exactly as described. If the terminals of one transformer winding be reversed, thus inducing an imof this patent may be obtained for pulse in the wrong direction, the result will be that the original impulse is exactly neutralized and no sound is produced in a receiver placed in series with the talking coil secondary.

From the foregoing description, taken in connection with the accompanying drawing, the advantages of the construction and method of operation will be readily understood by those skilled in the art to which the invention appertains, and while I have described the principle of operation, together with the device which I now consider to be the best embodiment thereof, I desire to have it understood that the device shown is merely illustrative and that such changes may be made when desired as fall within the scope of the appended claims. 7

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A telephone talking coil comprising a pair of primary windings composed of two twisted wires helically wound, a core within the windings, and a secondary winding consisting of a single wire wound around the primary windings.

2. A telephone talking coil comprising a pair of primary windings composed of two twisted wires helically wound, a core within the windings, a secondary winding consisting of a single wire wound around the primary windings, a source of current having one terminal connected with the right end of one of the primary windings and the 7 of a talking coil comprising primary windings composed of a twisted pair of wires helically wound, and a secondary winding inductively related thereto, a source of current connected with the right end of one JOHN PATRICK FERRITER.

five cents each, by addressing the Commissioner of Patents, 1

washing'toml). 0. H 

